Fact Shortly after buying my 99 XLH the battery would not charge. Battery was new so I pulled out the manual and tested the regulator Showed to be bad. Called the dealer. They replaced it, no charge and the sporty was 9 years old, with 7000 miles on it. Haven't had a problem like that since. Trust them and have purchased two more great bikes from them 03 100th Anniversary FXDL and 08 RK Classic

 

Sorry Sporty Pig Did not see that it was cHarley that disagreed. Too much beer

 

Interesting thread....I had an electrical issue as well on a bike with 6,000 miles! Battery would sometimes fail to power starter. Problem continued after replacing the battery. Checked things out with a multimeter and determined that stator was putting out plenty of current, suggesting that the voltage regulator was bad. Replaced the Voltage regulator and now everything works fine.

 

The late model HDs have three phase alternators, consisting of a stator (stationary windings bolted to the crankcase) and a rotor (half dozen permanent magnets glued to a metal dish which rotates on the left end of the crankshaft). Imagine three separate alternators with the positive and negative peaks of the sine waves occuring at intervals of 120 degrees of rotation.
The third main component is the voltage regulator and rectifier which bolts onto the frame ahead of the engine. It converts the three AC inputs (which are phase shifted) to a relatively smooth DC output and then regulates the voltage of that DC output to be compatible with the operating voltage of the fourth main component, the battery, or approximately 13.8-14.2 volts. So, it's a fairly complicated bit of electronics and depends on being able to radiate waste heat to the atmosphere. This is why chrome covers are a bad idea, like wrapping the Regulator/Rectifier in a blanket.
The alternator is relatively simple. Essentially three long pieces of wire each wrapped around four pole pieces, twelve total. One end of each of these wires is joined to the other two, joining them electrically. The other ends exit as the three AC leads. As the rotor's magnetic poles pass by these windings, they induce current to flow in the stator. If the Rect./Reg. is doing it's job, the output from it charges the battery, or just passes a little through (due to internal resistance of the battery) with the rest running the system--if the battery is fully charged.
The problem is that the diodes (one way valves, sorta) which accomplish the conversion from AC to DC can fail in two modes. Open, in which case it takes out at least one phase of the alternator, or shorted, meaning that the stator becomes the load. It heats up, increasing the resistance and that leads to more heating which further increases the resistance........you see where this is headed. This can also happen if the DC outputs are shorted together before any other load is supplied, like the battery or the rest of the electrical system. It was relatively common on the older (single phase) bikes to short at the plug where the stator plugged into the wiring harness. More common with the Big Twins, being right up in front where all the rain and goo would hit it.
There has apparently been a rash of Reg./Rec. problems in the Dynas, too. I found out about it on some blogs and so carried a spare along with the allen wrench to change it, on my recent mainland trip. I didn't need it.

 

I've lost 2 stators and 2 voltage regulators.

 

If your alternator stator goes, ask to look at the plug on it and on the wiring harness. If the pins look corroded, dirty, or burnt, suspect some contamination, probably water, in the plug. One of the dangers of frequent washing or riding in the rain.

 

i just got my bike back this week. it was the voltage regulator. good to go now.